Excitation energy transfer in the Li-Cs collision: Li*(2P)+Cs(6S)→Li(2S)+Cs*(5D)

1993

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inAbstract. The collisional excitation transfer for the processes Rb*(5P3/2)+K(4SI/2)~Rb(5Sm)+K*(4Pj), J = 1/2, 3/2, was investigated using two-photon laser excitation technique with a thermionic heat-pipe diode as a detector. The population densities of the K 4Pj levels induced by collisions with excited Rb atoms as well as those produced by direct laser excitation of the potassium atoms were probed through the measurement of the thermionic signals generated due to the ionization of the potassium atoms emerging from the K(4Pj) ~ K(7S1/2) excitation channel. The measurements of the thermionic signals in addition to the spectroscopic determination of the potassium number density yield the following values for the excitation transfer cross sections: a 1 (Rb 5 193/2 --~ K 4pro)=8 ~2 and o-2(Rb 5P3/z~K 4P3/2)= 11 ~2 The accuracy of the presented results is T-15%. The obtained results are compared to those for the opposite processes K* (4 Pj) + Rb (5 S~/2) --* K (4 S1/2) + Rb* (5 P3/2).

Section: K~/2)(av')'nk(4~/2)/n~(4p1/2) Which Is Equal To K /2)(a V')mentioning

confidence: 77%

The collision cross sections for excitation energy transfer in Rb(5P 3/2) + K(4S 1/2) → Rb(5S 1/2) + K(4P J ) processes

Horvatić

Vadla

1993

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“…The present investigation on excitation energy transfer occuring in the Cs(6P1/2) + K(4S1/2) -~ Cs(6P3/2) + K(4Sz/2) collision process, is part of a series of systematic investigations of the coltisional energy transfer in mixed alkali vapours [1][2][3][4][5][6][7][8]. To our knowledge, this process has never been investigated before.…”

Section: Pacsmentioning

confidence: 94%

“…Therefore, applying (2) and neglecting the rate D in the denominator, the rate C can be expressed in the following way:…”

Section: Pacs: 3450; 3200mentioning

confidence: 99%

The collision cross sections for the fine-structure mixing of caesium 6P levels induced by collisions with potassium atoms

Horvatić

Vadla

et al. 1996

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Abstract.The cross section for the fine-structure excitation transfer Cs(6P~/2) --* Cs(6P3/2), induced by collisions with the ground state potassium atoms, has been measured by resonant Doppler-free two-photon spectroscopy. The population densities of caesium 6Pj (J = 1/2, 3/2) levels were probed by thermionic detection of the collisionally ionized caesium atoms from the Cs(6Pj) -~ Cs(10S1/2) excitation channel. The cross section for the transfer process at the temperaoture T = 503 K 2 0 has been found to be o-(1/2 ~ 3/2) = 45 A + 20 Vo. The result is compared with previously published experimental cross sections for fine-structure transfer in resonance states of other alkali elements perturbed by potassium and a thoeretical value of the Li(2Pj)-K system calculated in a simple approach. PACS:34.50; 32.00The present investigation on excitation energy transfer occuring in the Cs(6P1/2) + K(4S1/2) -~ Cs(6P3/2) + K(4Sz/2) collision process, is part of a series of systematic investigations of the coltisional energy transfer in mixed alkali vapours [1][2][3][4][5][6][7][8]. To our knowledge, this process has never been investigated before. The data published so far in literature on cross sections for fine-structure mixing in alkalis induced by potassium include results for Na*-K [8, 9], K*-K [10-12], and Rb*-K [3] systems. However, these data are so scattered that, for example, a dependence of the cross sections on the fine-structure splittingAEfs of the resonance states can hardly be seen. The present results, although not completing the set of the data for alkali* -K systems, may help to answer the question of the o-vs. AEfs dependence. The missing data for Li*-K system, are very hard to obtain experimentally due to the spectral interference of the Li resonance lines with the potassium B-X molecular band. However, the data can be calculated quite reliably applying a simple but justified model [1, 6].The experimental arrangement, not shown explicitly, was similar to that reported previously [5]. A very small amount of caesium was added to the distilled potassium metal contained in the middle of the stainless steal heatpipe with Pyrex glass windows. The cental region of the heat-pipe was resistively heated to temperatures between 475 K and 530 K. Argon was used as a buffer gas, and its typical pressure, measured by MKS baratron manometer, was 53 Pa. In the experimental temperature range the metal-vapour pressure varied from 1.6 to 9.8 Pa, i.e., the heat-pipe was not operated in heat-pipe mode. In order to utilize the heat-pipe for the thermionic detection of the collisionally produced ions [13], a molybdenum filament 0.25 mm in diameter was built in.Caesium atoms were excited to the 6P1/2 state by the radiation from single-mode frequency stabilized laser diode (Mitsubishi ML 2701, 2 = 895 nm at 24 °C, maximal power: 8 roW). The laser beam was expanded and after passing through the circular aperture (diameter: 2 ram) its power was attenuated by neutral density filters. In order to improve the signal-to-noise ratio of th...

“…A review of the literature reveals that there is in the case of excitation transfer processes involving alkali atoms in resonance states and similar or dissimilar ground state alkali atoms considerable disagreement between experimental values of different groups as well as between experiment and theory [6,12]. As a rule, the calculated cross sections, which take into account only the first term in the multipole expansion of the long-range interaction potential, are too small and higher order terms have to be taken into account [13,14]. Therefore, it is especially favourable to test systems where one has access to good quality potential curves enabling numerical as well as analytical treatment of the collision.…”

Section: Introductionmentioning

confidence: 98%

Collisional excitation transfer between lithium isotopes

Brust

Veža

et al. 1995

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Abstract. Excitation transfer between the 3S~/2 states of the lithium isotopes 6Li and 7Li is measured in a thermionic diode. The 3S level is excited by off-resonant two-photon transitions with a single mode ew laser. The relative densities of the directly excited and collisionally populated levels are probed by further laser excitation to the 12P levels. An energy transfer cross section of 585 •2___ 160 ~2 is found at the experimental temperature of about 850 K. A simple semiclassical calculation yields a cross section of 450 A 2.